Photochemical functionalization of diazines: metal-free vinylation and phosphonylation

Under mild UVA irradiation, the CBr bond of bromodiazines can be activated to generate the corresponding radical intermediate. In the presence of alkynes, alkenylation reactions occurred to afford vinyl pyrimidine in moderate yields. Csp2-phosphorous bond can also be easily created in a photochemical version of the Arbuzov reaction. With UVA and a stoichiometric amount of trimethyl phosphite, the corresponding phosphonates were isolated in good to high yields. Very interesting selectivities were observed under these mild irradiation conditions. Functionalized substrates can be engaged and the resulting products could be further derivatized.

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